Europhys. Lett.
Volume 70, Number 4, May 2005
Page(s) 541 - 547
Section Interdisciplinary physics and related areas of science and technology
Published online 22 April 2005
Europhys. Lett., 70 (4), pp. 541-547 (2005)
DOI: 10.1209/epl/i2004-10510-1

Salt-induced condensation in actin-DNA mixtures

O. V. Zribi1, H. Kyung1, R. Golestanian2, 3, T. B. Liverpool2, 4 and G. C. L. Wong1

1  Department of Materials Science & Engineering, Department of Physics Department of Bioengineering, University of Illinois at Urbana-Champaign Urbana, IL 61801, USA
2  Isaac Newton Institute for Mathematical Sciences - Cambridge, CB3 0EH, UK
3  Institute for Advanced Studies in Basic Sciences - Zanjan 45195-159, Iran
4  Department of Applied Mathematics, University of Leeds - Leeds LS2 9JT, UK

received 19 October 2004; accepted in final form 24 March 2005
published online 22 April 2005

Multivalent ions can induce condensation of like-charged polyelectrolytes into compact states, a process that requires different ion valence for different polyelectrolyte species. We have examined the trivalent ion-induced condensation behavior in binary anionic polyelectrolyte mixtures consisting of DNA coils and F-actin rods, and observe a micro-phase separation between the two polyelectrolytes into coexisting finite-sized F-actin bundles and DNA toroids. Further, by increasing the DNA volume fraction in the mixture, condensed F-actin bundles can be completely destabilized, leading to only DNA condensation within the mixture. We examine a number of possible causes and propose a model based on polyelectrolyte competition for ions.

82.35.Rs - Polyelectrolytes.
82.35.Pq - Biopolymers, biopolymerization.
87.15.Aa - Theory and modeling; computer simulation.

© EDP Sciences 2005